/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.transformation.dag.transformer.multi;

import org.apache.iotdb.db.exception.query.QueryProcessException;
import org.apache.iotdb.db.mpp.transformation.api.LayerPointReader;
import org.apache.iotdb.db.mpp.transformation.api.YieldableState;
import org.apache.iotdb.db.mpp.transformation.dag.udf.UDTFExecutor;
import org.apache.iotdb.tsfile.exception.write.UnSupportedDataTypeException;

import java.io.IOException;

public abstract class UniversalUDFQueryTransformer extends UDFQueryTransformer {

    protected final LayerPointReader layerPointReader;
    protected final boolean isLayerPointReaderConstant;

    protected UniversalUDFQueryTransformer(UDTFExecutor executor) {
        super(executor);
        layerPointReader = executor.getCollector().constructPointReaderUsingTrivialEvictionStrategy();
        isLayerPointReaderConstant = layerPointReader.isConstantPointReader();
    }

    @Override
    protected final YieldableState yieldValue() throws QueryProcessException, IOException {
        while (!cacheValueFromUDFOutput()) {
            final YieldableState udfYieldableState = tryExecuteUDFOnce();
            if (udfYieldableState == YieldableState.NOT_YIELDABLE_WAITING_FOR_DATA) {
                return YieldableState.NOT_YIELDABLE_WAITING_FOR_DATA;
            }
            if (udfYieldableState == YieldableState.NOT_YIELDABLE_NO_MORE_DATA && !terminate()) {
                return YieldableState.NOT_YIELDABLE_NO_MORE_DATA;
            }
        }
        return YieldableState.YIELDABLE;
    }

    @Override
    protected final boolean cacheValue() throws QueryProcessException, IOException {
        while (!cacheValueFromUDFOutput()) {
            if (!executeUDFOnce() && !terminate()) {
                return false;
            }
        }
        return true;
    }

    protected abstract YieldableState tryExecuteUDFOnce() throws QueryProcessException, IOException;

    protected abstract boolean executeUDFOnce() throws QueryProcessException, IOException;

    protected final boolean cacheValueFromUDFOutput() throws QueryProcessException, IOException {
        if (!layerPointReader.next()) {
            return false;
        }
        cachedTime = layerPointReader.currentTime();
        if (layerPointReader.isCurrentNull()) {
            currentNull = true;
        } else {
            switch (tsDataType) {
                case INT32:
                    cachedInt = layerPointReader.currentInt();
                    break;
                case INT64:
                    cachedLong = layerPointReader.currentLong();
                    break;
                case FLOAT:
                    cachedFloat = layerPointReader.currentFloat();
                    break;
                case DOUBLE:
                    cachedDouble = layerPointReader.currentDouble();
                    break;
                case BOOLEAN:
                    cachedBoolean = layerPointReader.currentBoolean();
                    break;
                case TEXT:
                    cachedBinary = layerPointReader.currentBinary();
                    break;
                default:
                    throw new UnSupportedDataTypeException(tsDataType.toString());
            }
        }
        layerPointReader.readyForNext();
        return true;
    }

    @Override
    public final boolean isConstantPointReader() {
        return isLayerPointReaderConstant;
    }
}
